Making ethylenediaminetetraacetic acid

Abstract

Provided is a method of making ethylenediaminetetraacetic acid (EDTA) comprising the steps: (a) providing a reaction mixture (a) comprising ethylenediamine (EDA) and glycolonitrile (GN), wherein reaction mixture (a) comprises 0% to 0.1% by weight, based on the weight of reaction mixture (a), of any base having pKa of the conjugate acid (PKaH) of 13 or higher; (b) causing or allowing reaction mixture (a) to react to form a dinitrile (DN) compound; (c) bringing the DN into contact with aqueous solution of a base having pKaH of 11 or higher, and causing or allowing the resulting mixture to react to form a diacid compound (DA); (d) causing or allowing the DA to react, either sequentially or simultaneously, with additional GN to form products (Pd); (e) causing or allowing products (Pd) to react with a base having pKaH of 11 or higher, to form EDTA. Also provided is a composition comprising a diacid/dinitrile compound (DADN) wherein each —R has the structure:

Dependencies are inferred from the claim text.